Many people engage in the baking of breads and similar foodstuffs in their homes. The most common home making of bread requires that flour be mixed with ingredients such as yeast, water and others which suit the taste. The ingredients are mixed together to form a pasty mass of dough. Typically a yeast, such as baker's yeast, is added at about 2 weight percent to the dough. Yeast is included so that it will generate carbon dioxide gas by fermenting sugars such as glucose, fructose, maltose, and sucrose which are present in the dough. Other yeast activity products also flavor the baked product and alter the dough's physical properties. For the living yeast cells to perform their desired function, they must be heated somewhat above room temperature.
The carbon dioxide gas evolved must be retained within the dough mass and this is facilitated by presence in the dough of gluten which is the protein part of the wheat berry. As a result of mechanical activity caused by kneading of the dough, gluten forms an elastic substance which enables the dough to retain, as a fine array of bubbles, the gas generated by the yeast.
Thus, consistency in the steps of kneading of the dough, and causing the yeast to become active by moderate heating, are important in the manufacture of quality home baked products. However, the home bread making process is typically inconsistent. The normal routine which is followed is to spiritedly push and fold the dough mass for a period of time. This activity is commonly carried out on a smooth counter top or bread board, at room temperature of about 68.degree. F.(20.degree. C.). The next step commonly used, as taught by most baking recipe books, is to put the kneaded dough in a common bowl, as a large ball covered by a damp cloth. This is put in a warm place, such as a warm oven, or on a room heater, etc. Over a period of time the heat from the environment will penetrate the dough, increasing the activity of the yeast, thereby causing the dough to rise by action of the expanding gases. Of course, the environment cannot be too warm, elsewise the yeast may be killed.
Traditionally, a dough rising period may be from one-half to five hours, depending on the temperature of the environment. One of the principal reasons such a long time may be required is that it takes time for the heat to penetrate through the mass of dough due to its shape. On the other hand, care must be taken to not "over rise" the dough--that is, allow the dough to rise for too long a time--because an unpleasant yeasty taste may result. Ultimately, the dough may even deflate and fall back on itself. Conversely, if the dough does not rise sufficiently, then the texture will be heavy and glue-like. The preferred rise of the dough is reached by the dough having approximately doubled in size. Again, due to the shape of the dough mass when the latter is put into a bowl or the like to rise, it is difficult for the occasional baker to accurately judge when the doubling in size has occurred.
After rising, the bread dough is typically "punched down", meaning that it is deflated and kneaded again. The object of this step is to give the bread an even texture and to get rid of the larger gas bubbles. Then, the dough is allowed to rise again, in essentially a repeat of the first step. As the yeast is continuing to ferment, additional punchings and risings may be utilized. Finally, the dough is put in an oven and heated to a high temperature in the baking step.
As should be evident, the carrying out of the kneading and rising operation requires attention to detail and is time consuming. In addition variations in the temperature of the room and the temperature during the rising step can affect the result. Naturally, commercial bakers use specialized equipment, including chambers having a controlled temperature and humidity environment. See for instance, U.S. Pats. Nos. 3,518,949 to Stock and 3,456,598 to McKay. Obviously equipment that is in commercial use is not suited for home baking of bread because of cost and complexity.
In U.S. Pat. No. 3,418,453, Sparks discloses an electrically heated dough raising oven suited for home use. The oven is essentially a cardboard box having a light bulb as a heating source. The dough, contained in pans, is placed in the chamber and heated by convection of the air within. Weiss in U.S. Pat. No. 4,210,073 discloses a portable environmental chamber which is useful in rising or proofing of dough. Basically, dough which is contained in a bowl standing on a flat surface is enveloped in a tent-like device. The tent-like covering has included in its surface heating elements which, by a combination of radiation and convection, heat the dough in the bowl. These prior art devices are helpful in providing better control of the dough temperature but, the time and uniformity of rising will still be limited by the fact that the dough is heated as a roughly spherical mass, from the exterior. Also, different shapes of dough masses will have different rising times, contributing to variability in the end product.
As will be apparent from the foregoing, the occasional home-bread baker will encounter problems relating to the ability to detect when the dough has risen to its preferred volume, i.e., has doubled in size, and relating to the time needed to enable the dough to rise in the preferred manner. The prior art has recognized that a dough mass should be monitored while rising to ensure that it has doubled in volume during each rising step. For example, U.S. Pat. No. 1,429,269, issued Sept. 19, 1922 to A. J. Banks discloses a fermentation meter which serves to monitor and measure the degree of expansion of a rising mass of dough. U.S. Pat. No. 2,507,425, issued May 9, 1950 to C. D. Swartout discloses a compound container and lid which contains a rising mass of dough and provides an indication of the degree to which the dough mass has risen. U.S. Pat. No. 1,654,897, issued Jan. 3, 1928 to A. A. Rosenblum discloses an apparatus for testing and detecting the amount of rise which a fermenting mass of dough undergoes. The aforesaid concepts disclosed in these patents are subject to certain problems of accuracy and time due principally to the shape of the dough mass as it is set aside to rise. We address these problems in the following manner.